1. Field of the Invention
The present invention relates to a single yarn-adhered sheet and a method and apparatus for producing the sheet, and more particularly, to a method and apparatus for producing a single yarn-adhered sheet on which dense channels are formed.
2. Description of the Related Art
Conventionally, food items including meat or processed meat products, which are required to be kept in storage for a long period of time, are put in a vacuum-available vinyl pack and vacuumized by using an air pump or other vacuum device, the inlet thereof is sealed, and the pack is then kept in storage.
In order to manufacture a vacuum packaging vinyl pack, Korean Laid Open Publication No. 2002-68468 discloses a method for forming embossed portions on one surface, and Korean Patent Registration No. 465508 discloses a method of adhering single yarns to a sheet.
The related art method of adhering single yarns to a sheet is illustrated in FIG. 1. In the related art, a general thermoplastic resin is inserted into a body 71 of an extruder 70 having a nozzle unit 72 with a plurality of extrusion holes 73 formed at regular intervals and extruded to directly produce single yarns 1, and the produced single yarns 1 are adhered to a sheet, thus integrating the process of producing the thermoplastic resin single yarn and the process of producing the sheet.
In detail, as shown in FIG. 1, thermoplastic resin single yarns 1 output from the extruder 70 are transferred to an upper laminating roll 22 through a single yarn roll 80 having supply recesses 81 formed at regular intervals thereon and a guide roll 10 having guide recesses 11 formed therein, and in this case, because the thermoplastic resin single yarns 1 extruded by the extruder 70 are in a molten state, the single yarns 1 are solidified through the single yarn supply roll 80 having a cooling effect, and then transferred to the guide roll 10. The thermoplastic resin single yarns 1, with an outer surface thereof slightly melted by a heater 4, are adhered to and compressed with a sheet 2, which has been transferred to a lower laminating roll 21 after being supplied from a sheet supply roll 30, by a laminating roll 20 to form a vacuum packaging sheet 3 having a channel layer in which the single yarns 1 and the sheet 2 are adhered. The adhered sheet 3 is wound on and around a winding roll 60 through a cooling roll 50 so as to be completed as a sheet having single yarn protrusions.
FIG. 2 is a bottom perspective view of the extruder of the apparatus for producing a single yarn-adhered sheet according to the related art as illustrated in FIG. 1. The extruder 70 includes the body 71 storing a general thermoplastic resin and the nozzle 72 part formed at a lower end portion of the body 71 and having a plurality of extrusion holes 73 formed at regular intervals therein. With the resin existing in a molten state in the body 71 of the extruder 70, the plurality of synthetic resin single yarns 1 are extruded from the extrusion holes 73 of the nozzle unit 72.
However, the related art has a problem in that because the producing of the single yarn and the adhering of the single yarn are performed separately, the producing method and the producing apparatus are complicated and an additional heating operation must be performed.
In addition, as shown in FIG. 3, the diameter (D) of the resin extruded from the extrusion hole 73 extends as it is adhered to the single yarn supply roll 80 and rotated, and as a result, the resin having the extended diameter (d) is adhered to the single yarn supply roll 80.
Thus, because the diameter (d) of the adhered single yarn is smaller than the diameter (D) of the resin from the extrusion hole 73, the intervals between the extrusion holes 73 become wider when the resin is adhered to the single yarn supply roll 80. In particular, a certain distance needs to be maintained between the extrusion holes 73 to prevent the resin from being attached at an initial stage, having a limitation in narrowing the interval between the single yarns. In addition, when the sheet obtained with the intervals between single yarns not sufficiently narrowed is formed as a vacuum vinyl pack, a vacuum suction is not smoothly performed, and this problem is an obstacle to the related art in being put into practical use.